What does the record-level access in Sharing Rules mean?

When you enable record-level access for a module, then the records in the module are accessible only to their owners and co-owners.
Follow these steps to set the sharing rules to record-level access:

1. Click the User Menu on the top right corner of the screen.
2. Click the Settings button.
   • You will land on the Settings page.
3. Look for the User Management section.
4. Select Sharing Rules.
5. Select a module and enable the radio button under the Record Level Access column.
6. Click the Apply New Sharing Rules button.